
In the 1960s, Japanese biologist Motoo Kimura introduced the neutral theory of molecular evolution. It advanced the idea that most random DNA mutations are not driven by survival of the fittest but by pure chance. Now a team of scientists at the University of Michigan has published a new study saying that beneficial mutations arise more frequently than Kimura had believed. However, they say that a changing environment often prevents those mutations from spreading through an entire population. In other words, environments change more quickly than mutations can spread through populations.
Random DNA mutations arise by chance, and natural selection removes the unhelpful ones. The new study determined that only 1% of amino acid mutations are beneficial. That doesn’t sound like a very big percentage, but it is larger than what Kimura suggested. Even then, those mutations don’t spread to the entire population of a species.
To conduct this study, researchers at the University of Michigan used yeast cells, which live for only 3 hours. That brief generational time allowed them to study 1320 yeast populations over 800 generations using 100 different growth media to create different environments. Environmental changes effectively erased a mutation’s advantage before it could spread through an entire population. In addition, mutations that are beneficial in one environment are usually harmful in another.
In all research, random DNA mutations have not been shown to create new species or higher orders, but they do change and refine existing species. Even with mutations in yeast populations, whether they were beneficial or otherwise, the result was still yeast. The same could be said in other cases, such as dogs or cattle, where we can see mutations resulting in new variations among those animals, but they still remain dogs or cattle.
As we have said before, microevolution does not prove macroevolution. Even if the uncommon mutations are beneficial, they are often lost because they don’t spread through the entire population. Evolution cannot explain the diversity of life on planet Earth.
— Roland Earnst © 2026
Reference: msn.com









